I think you might be a tad late. The ARC Europe fleet left Bermuda for the Azores on May 20, so the largest organized crossing rally is done for this year. I don't know of any others. Possibly there is a yacht club or owner's group that has organized such a rally, but I'm not familiar with them. The two gathering grounds in the Caribbean for the annual crossing to the Med are the Virgin Islands and St. Maarten. In the past, the boats left closer to the end of April than now, I haven't heard much about this year.
Hurricane season starts June 1, though it's a rare hurricane that develops this early. However, in June the tropical depressions and tropical waves start rolling across the Atlantic and can offer some pretty uncomfortable weather.
Sorry I can't help further.
P.S. See StormW's report Tropical weather